1. Technical Field
The present invention relates to a corrected value calculation method and a printing device.
2. Background Technology
One example of a fluid ejection device is an inkjet printer (hereinbelow, a printer) in which ink (a fluid) is ejected from nozzles provided to a head to form an image. Such printers include those in which a plurality of rectangular heads are aligned in a paper width direction, and ink is ejected from the heads onto a medium conveyed below the heads to form an image.
In such a printer, there is a portion where the ends of the heads overlap in the direction of nozzle alignment, i.e., in the joint of the heads (hereinbelow referred to as the “overlapping region”). With such a configuration, the heads are disposed separated in relation to their relative movement direction with the medium, and the deposited positions of the ink are therefore sometimes misaligned because of shifting of the medium. As a result, density changes occur in the overlapping region, but there is also a technique for performing a density correction for each raster line (also referred to as a pixel column) in order to correct these changes. With this technique, a test pattern is printed, a correction is performed such that less ink is ejected from nozzles that tend to form raster lines of high density, and a correction is performed such that more ink is ejected from nozzles that tend to form raster lines of low density.
Patent Citation 1 shows that the discharge amount is corrected so that the amounts of ink discharged from the heads are constant. Patent Citation 2 discloses a printer in which the ends of the heads (part of the nozzles columns) are made to overlap and a plurality of heads are disposed.
Japanese Patent Application Publication No. 2010-188632 (Patent Citation 1) and Japanese Patent Application Publication No. 2009-226904 (Patent Citation 2) are examples of the related art.